Polymeric membrane pervaporation

Current research on the blends of natural and synthetic polymers as new biomaterials: Review

Chitin and chitosan are considerably versatile and promising biomaterials. The deacetylated chitin derivative chitosan is a useful and interesting bioactive polymer. Despite its biodegradability, it has many reactive amino side groups, which offer possibilities of chemical modifications, formation of a large variety of beneficial derivatives, which are commercially available or can be made available via graft reactions and ionic interactions. This study looks at the contemporary research in chitin and chitosan towards structure, properties, and applications in various industrial and biomedical fields.

A Review on Chitin and Chitosan Polymers: Structure, Chemistry, Solubility, Derivatives, and Applications

The article contains sections titled: 

1.	Introduction	
2.	Molecular Structure and Conformation	
2.1.	Chitin	
2.2.	Chitosan	
3.	Raw Materials and Production	
3.1.	Isolation of Chitin from Crab and Shrimp Shells	
3.2.	Preparation of Chitosan from Chitin	
4.	Metabolism and Biosynthesis	
5.	Chemical Properties	
5.1.	Reactions on the Amino Group	
5.1.1.	N-Acylation	
5.1.2.	Formation of N-Alkylidene and N-Arylidene Derivatives	
5.1.3.	N-Alkylation and N-Arylation	
5.2.	Reactions at the Hydroxyl Group	
5.3.	Reactions at C-6	
5.4.	Graft Polymerization on Chitin and Chitosan	
6.	Application Forms and Formulations	
7.	Uses	
8.	Economic Aspects	
9.	Toxicology and Environmental Aspects

Chitin and Chitosan

Membranes for the dehydration of solvents by pervaporation

Pervaporation with chitosan membranes II. Blend membranes of chitosan and polyacrylic acid and comparison of homogeneous and composite membrane based on polyelectrolyte complexes of chitosan and polyacrylic acid for the separation of ethanol-water mixtures

Chitosan/N-methylol nylon 6 blend membranes for the pervaporation separation of ethanol–water mixtures

On the basis of solution-diffusion mechanism and incorporation of a pseudophase-change phenomenon, the pseudophase-change solution-diffusion (PPCSD) model is developed for pervaporation of a binary mixture through a membrane system. Flux equations of individual components thus derived clearly describe the role of coupling flux in pervaporation and show that it depends mainly on the solubility and mobility of the other component in the membrane. Good agreement is found between the theoretical and experimental results (from literature values for the hexane-heptane-polyethylene system). In addition to the solubility and mobility of individual component, the pervaporation performance of a membrane is influenced by the effect of plasticization and coupling flux, especially when strong interaction, occur between the permeants and the membrane. A parameter study indicates that both plasticizing and coupling effects enhance the permeation rate and usually lead to a decrease in membrane permselectivity.

A Pseudophase-Change Solution-Diffusion Model for Pervaporation. II. Binary Mixture Permeation

Crosslinked blended membranes of poly(vinyl alcohol) (PVA) and N-methylol nylon-6 were prepared either by thermal crosslinking at 180°C or by chemical crosslinking with maleic acid. The pervaporation performance for the separation of ethanol–water mixtures of these membranes was investigated in terms of feed concentration, PVA content, and crosslinking agent content. The pervaporation performance of two differently crosslinked membranes was strongly influenced by the nature of the crosslinkage. Significant improvement in the pervaporation separation index can be achieved for chemically crosslinked membranes. From the comparison between the pervaporation and sorption tests, it is suggested that, for hydrophilic membranes, sorption properties dominate the pervaporation performance at feed solutions of higher water content, while diffusion properties govern at feed solutions of higher ethanol content. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 317–327, 1998

Crosslinked blended poly(vinyl alcohol)/N-methylol nylon-6 membranes for the pervaporation separation of ethanol-water mixtures

N-methylol nylon 6 membranes were prepared by reacting nylon-6 with formaldehyde. Elemental analysis, used to analyze the composition of modified membranes, showed that the degree of substitution increased with formaldehyde content in the reaction solution. The modified nylon-6 membranes exhibited a high affinity to ethanol. Pervaporation results for the separation of ethanol-water mixtures showed that these membranes were water-selective, indicating that the diffusion property is the dominant factor. An N-methylol nylon-6 membrane with 33% degree of substitution showed the best membrane performance. In order to control the swelling of N-methylol nylon-6 membranes in the feed solutions of high ethanol content, thermal crosslinking was applied at 180°C for different times. It was found that heat treatment of 10 minutes gave the optimal permselectivity. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 855–863, 1997

Jyh-Jeng Shieh

Papers

Pervaporation with chitosan membranes II. Blend membranes of chitosan and polyacrylic acid and comparison of homogeneous and composite membrane based on polyelectrolyte complexes of chitosan and polyacrylic acid for the separation of ethanol-water mixtures

Chitosan/N-methylol nylon 6 blend membranes for the pervaporation separation of ethanol–water mixtures

A Pseudophase-Change Solution-Diffusion Model for Pervaporation. II. Binary Mixture Permeation

Crosslinked blended poly(vinyl alcohol)/N-methylol nylon-6 membranes for the pervaporation separation of ethanol-water mixtures

Preparation of N-methylol nylon-6 membranes for pervaporation of ethanol-water mixtures